I will admit...when I got my AR, I did not think there was a difference between the two rounds.

However, I did end up buying mine that shoots both rounds and it shoots both of them very well. I tend to use just FMJ ammo in mine, but that is only because it is generally the cheapest and most available in my area. I love the platform regardless of whether I am shooting .223 or 5.56X45.

It is interesting that Hornady would produce a round in a steel case, especially under their TAP label. Wonder what the Wolf haters would say about that???? At less than $.30 a round, for plinking, it's a relative bargain...

steel case v. brass is hardly a tweak--it is cheap practice ammo loaded to .223 specs. Again I am surprised that Hornady would market this stuff under their TAP name...For the price, I would rather shoot PMC through mine and reload the brass...

It is interesting that Hornady would produce a round in a steel case, especially under their TAP label. Wonder what the Wolf haters would say about that???? At less than $.30 a round, for plinking, it's a relative bargain...

I'm pretty sure Wolf haters do so because it is smelly, less accurate, less powerful, and less reliable than many other brands of ammo.

Since I am pretty sure Hornady isn't producing their steel cased ammo to the same low standards, it would stand to reason that it can't be as cheap as Wolf, or that Wolf haters wouldn't necessarily have a problem with it.

True 5.56 is loaded to higher pressures than most commercial .223...I purchased some factory Federal American Eagle .223 55FMJ years ago that was loaded so hot it expanded the primer pockets (on the first firing) and the brass was junk. This could have been caused by using a 5.56 NATO load in a commercial case (non crimped primer or soft brass). Higher chamber pressures of 5.56 recommend a 5.56 chamber, Mike.

Hornady 75gr TAP and Speer Gold Dot 64gr JSP are both currently offered as factory .223 Remington and 5.56x45mm NATO. The velocity difference can be as little as +/-50fps, depending on the gun/lot.

I issue both 5.56 and .223 duty and practice ammunition at my department. One of the best patrol rifle rounds out there (Federal Bonded Tactical 62gr JSP, as used by DEA) is available only in .223.

I have not seen anything supporting .223 being less accurate in general in a 5.56 chambered rifle. Improper combinations of barrel length/twist and bullet weight/type are much more likely to cause unacceptable accuracy in my experience.

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So from what I'm reading, it is perfectly fine to shoot .223 out of a 5.56 barrel and there are negligible effects on performance. The weight and grain of the barrel would affect performance and the twist rate much more.

So .223 out of a 5.56 marked receiver and bbl is just fine, but 5.56 out of a .223 mark receiver bbl is not. Matching proper twist rate and bullet weight is more important, but there is no harm to hte rifle shooting hte lower pressured 223 out of a barrel meant for 5.56.

Thats the way I understood it before, but I seem to have confused myself